Clean Regulatory Profile - No CMR · Not Repr. 1B · No REACH SVHC · No Annex XIV/XVII · Non-HAP · Medical-Grade Compliance Supported: TOPM (CAS 3126-80-5) is not classified as a reproductive toxicant, carcinogen, or mutagen under EU CLP 1272/2008. Not on REACH SVHC Candidate List; not subject to REACH Annex XIV or Annex XVII. Confirmed non-HAP (EPA CompTox), TSCA-listed. Flash point ≥265°C - effectively no vapour hazard at ambient. Industry-recognised ultra-low-toxicity medical-grade DEHP replacement for PVC medical devices. REACH registration confirmed (ECHA EC 221-548-9). Full compliance documentation provided with every shipment.
Four-Ester Aromatic Synthetic Ester · High-Temperature Chain Oil · Medical-Grade PVC · No CMR
TOPM - Tetraoctyl Pyromellitate
(TEHPM / Tetra(2-ethylhexyl) Pyromellitate / Tetra(2-ethylhexyl) Benzene-1,2,4,5-tetracarboxylate)
| CAS No. | 3126-80-5 |
| EC Number | 221-548-9 |
| IUPAC Name | bis(2-ethylhexyl) 2,5-bis[(2-ethylhexoxy)carbonyl]benzene-1,4-dicarboxylate |
| Molecular Formula | C₄₂H₇₀O₈ (MW = 703.01 g/mol) |
| Structure | Benzene-1,2,4,5-tetracarboxylic acid (pyromellitic acid) + 4 × 2-ethylhexyl ester groups · Largest MW monomeric aromatic ester plasticiser |
| EU CLP / REACH | ✓ No CMR / No Repr. 1B ✓ No SVHC ✓ No Annex XIV / XVII |
| Flash Point / Safety | ≥265°C (actual 270°C) · Combustible Liquid Class III-B Zero vapour at ambient |
| US HAP / TSCA | ✓ Not a US EPA HAP ✓ TSCA listed |
| Key Performance | Evap. loss ≤1.5% (actual 1.0%) @ 250°C/1h VI ≥95 (actual 98) Pour point ≤−18°C (actual −27°C) |
| Grades Available | Industrial Grade Medical Grade (Pt-Co ≤50, heavy metals, ISO 10993 data) |
What Is TOPM? The Four-Ester Aromatic Synthetic Ester That Outperforms TOTM, DEHP & PAO
Tetraoctyl Pyromellitate (TOPM / TEHPM, CAS 3126-80-5) is the tetraester of pyromellitic acid (benzene-1,2,4,5-tetracarboxylic acid, PMDA) and 2-ethylhexanol - a benzene ring bearing four 2-ethylhexyl ester groups at all four ring positions. This four-ester aromatic architecture distinguishes TOPM from all other commercial synthetic ester plasticisers and lubricant esters: TOTM has three ester groups (trimellitate), DEHP/DOP has two (phthalate), and DIDP/DINP have two branched variants. Molecular formula C₄₂H₇₀O₈, MW 703.01 g/mol - the highest molecular weight among monomeric aromatic ester plasticisers, a directly measurable property that drives TOPM's lowest-in-class evaporation rate (1.0% at 250°C/1h), lowest migration from PVC matrices, and highest thermal-oxidative stability.
TOPM occupies two commercially distinct but equally important market positions. As a high-temperature chain oil ester base oil, TOPM's validated performance at 260°C/3h - least carbon deposition among all tested comparators including PAO, TOTM, polyol ester, and Group II mineral oil - makes it the preferred synthetic ester for oven conveyor chain lubrication in paint baking, food production, textile, and glass fibre manufacturing. As the industry-leading ultra-low-toxicity medical-grade PVC plasticiser, TOPM's no-CMR regulatory profile and negligible extraction from PVC matrices have established it as the primary DEHP replacement across IV bags, catheters, blood collection tubing, and surgical drainage systems globally.
Synthesis: TOPM is produced by esterification of pyromellitic dianhydride (PMDA) with 2-ethylhexanol under acid catalysis at 180–220°C under reduced pressure, followed by neutralisation, water washing, decolorisation, and dealcoholisation. The ≤0.1 mg KOH/g acid value specification confirms near-complete four-site esterification; ≤0.2‰ moisture reflects thorough post-reaction drying critical for hydrolytic stability.
Physical & Performance Properties of TOPM
TOPM Specifications - Industrial Grade & Medical Grade
| Specification Item | Industrial Grade | Medical Grade | Actual / Note |
|---|---|---|---|
| Appearance (25°C) | Colorless to pale yellow transparent liquid | Near-colorless preferred | Viscous, transparent liquid; no turbidity or particulate |
| Acid Value | ≤0.1 mg KOH/g | ≤0.05 mg KOH/g | Actual 0.05; near-complete esterification; protects against PVC thermal degradation |
| Moisture | ≤0.2‰ | ≤0.1‰ | Karl Fischer; actual 0.1‰; critical for hydrolytic stability during storage and PVC processing |
| Color (Pt-Co) | ≤100 | ≤50 + heavy metals | Medical: Pb, Cd, Hg, Cr batch testing per ISO 10993 raw material requirements |
| Density (20°C) | 0.991–0.997 g/cm³ | 0.991–0.997 g/cm³ | Actual 0.995 g/cm³; density meter verification each batch |
| Kinematic Viscosity (40°C) | ~ 172 mm²/s (actual) | ~ 172 mm²/s | High-viscosity-grade synthetic ester; reported on COA with both 40°C and 100°C values |
| Kinematic Viscosity (100°C) | ~ 16.3 mm²/s (actual) | ~ 16.3 mm²/s | Used with 40°C value to calculate VI via ASTM D2270 |
| Viscosity Index (VI) | ≥95 (actual 98) | ≥95 | Favourable vs Group II mineral oil (95–100); approaches PAO (100–120); verified per ASTM D2270 |
| Flash Point | ≥265°C (actual 270°C) | ≥265°C | Combustible Liquid Class III-B; no explosion-proof storage required; negligible vapour at ambient |
| Pour Point | ≤−18°C (actual −27°C) | ≤−18°C | Excellent cold-start performance; remains pumpable at temperatures above −18°C |
| Evaporation Loss (250°C, 1h) | ≤1.5% (actual 1.0%) | ≤1.0% | Lowest among commercial monomeric aromatic esters; critical for chain oil relubrication interval |
| EU CLP / REACH | No CMR ✓ No SVHC ✓ | No CMR ✓ FDA/MDR support ✓ | ISO 10993 cytotoxicity and haemocompatibility pre-screening data available for medical grade |
| Packaging | 200 kg drum / 1000 kg IBC / ISO tank | 200 kg drum (batch-specific COA) | Standard Combustible Liquid export documentation; no Class 3 Flammable Liquid DG restrictions |
High-Temperature Chain Oil Test Data - TOPM vs Comparators at 260°C/3h
Validated manufacturer experimental results: continuous high-temperature operation simulation at 260°C, 3 hours. Carbon deposition quantified gravimetrically; evaporation loss by weight difference at 250°C/1h. Standard EP anti-wear, antioxidant, and anti-foam additive package applied equally to all formulations.
| Lubricant Base | Carbon Deposition (260°C, 3h) |
Evap. Loss (250°C, 1h) |
Oxidation Stability | Pour Point |
|---|---|---|---|---|
| TOPM (4-ester pyromellitate) | Least ✓✓ | 1.0% ✓✓ | Excellent ✓✓ | −27°C ✓ |
| TOTM (3-ester trimellitate) | More than TOPM | ~1.5–2.0% | Very good | ~−30°C |
| Polyol ester (TMP/PE) | More than TOPM | ~2–3% | Good | −45°C to −60°C ✓✓ |
| PAO (Group IV base oil) | More than TOPM | ~2–4% (lower MW grades) | Good | Excellent ✓✓ |
| Group II mineral oil | Most deposition ⚠ | ~5–10% ⚠ | Moderate ⚠ | Limited ⚠ |
TOPM Applications - Two Dominant Markets, One Product
1. High-Temperature Chain Oil - Best-in-Class at 250–280°C
High-temperature chain oil applications - continuous conveyor chains in paint baking ovens (180–200°C), food production line ovens (200–250°C), textile tenter frames (160–220°C), and glass fibre production furnaces (>250°C) - represent TOPM's most technically demanding and most differentiated application. These chains require a lubricant that resists evaporation and oxidative degradation at continuous service temperatures where conventional lubricants either evaporate, decompose to carbon deposits (causing chain seizing and conveyor failure), or require impractically frequent relubrication.
TOPM's validated superiority at 260°C/3h is clear across all four performance dimensions (see test data table above): least carbon deposition (critical for chain cleanliness and coking interval extension), lowest evaporation loss at 250°C/1h at 1.0% (directly reducing lubricant consumption and relubrication frequency vs TOTM's ~1.5–2% and PAO's ~2–4%), excellent oxidative stability (extending drain interval), and pour point −27°C (enabling cold-start operation and unheated facility storage). In high-throughput industrial operations where unplanned conveyor chain downtime costs thousands per hour, TOPM's combination of lowest carbon deposition and lowest evaporation loss translates directly to longer relubrication intervals and fewer chain replacement events.
Typical TOPM chain oil formulation: TOPM 85–95% as base oil + 0.5–2% aminic antioxidant + 0.5–2% EP anti-wear agent (ZDDP or organic phosphate) + 0.1% anti-foam - meeting DIN 51825 or customer chain oil specification requirements. Contact Sinolook for formulation guidance.
2. Medical-Grade PVC - Industry-Leading DEHP Replacement for Medical Devices
The global shift away from DEHP (di(2-ethylhexyl) phthalate) in medical PVC - driven by DEHP's EU CLP Repr. 1B (H360FD) classification and REACH Annex XIV authorisation requirement - has established TOPM as the preferred ultra-low-toxicity plasticiser for the most demanding medical PVC applications. TOPM's position rests on three verified properties:
(1) Negligible extraction risk: TOPM's high MW (703 g/mol) and strong polymer-matrix compatibility reduce migration from PVC formulations to levels effectively undetectable in physiological fluid contact testing. Standard TOPM-plasticised PVC blood contact testing shows extraction well below the 0.1 μg/mL biological effects assessment trigger level.
(2) No reproductive toxicant classification: Unlike DEHP (Repr. 1B) and DINP/DIDP (Repr. 2 at high doses), TOPM carries no reproductive hazard classification under EU CLP or US NTP - enabling use in medical device formulations where CMR substances are excluded by regulation or industry standard.
(3) Established regulatory acceptance: TOPM-plasticised PVC has received acceptance in FDA-regulated medical device submissions (510(k) and PMA pathways) and EU CE-mark (MDR) technical file submissions across a broad range of device classes.
TOPM medical PVC applications include: IV bags and infusion sets, blood collection bags and tubing, haemodialysis blood lines, urinary catheters, nasogastric tubing, endotracheal tube cuffs, surgical drain tubing, device housings, and PVC-based organ substitute membranes. Sinolook's medical-grade TOPM includes enhanced COA (Pt-Co ≤50, heavy metals), batch-specific extraction test data, and ISO 10993 cytotoxicity / haemocompatibility pre-screening data for device technical files.
3. Industrial Lubricants - Additive Solubiliser in PAO / Group III/IV Base Oils
The shift to Group III (VHVI) and Group IV (PAO) base oils has created a formulation challenge: these highly refined, non-polar base oils have poor solvency for polar additive packages (ZDDP, amine antioxidants, friction modifiers, rust inhibitors) compared to the Group I oils they replaced. TOPM's four ester dipoles and aromatic core, added at 5–20% in PAO or Group III formulations, dramatically improve additive package solubility and compatibility - preventing additive dropout, phase separation on storage, and the loss of anti-wear and anti-oxidant performance that occurs in all-PAO formulations without a polar ester component.
Beyond additive solubilisation, TOPM contributes elastomer seal compatibility management: highly refined non-polar base oils cause seal shrinkage in fluorosilicone, NBR, ACM, and HNBR seals; TOPM's ester polarity moderates this effect, maintaining seal dimensional stability. The addition level for seal compatibility (1–5%) is lower than for additive solubilisation (5–20%), allowing a single additive to address both functions. As a primary synthetic base oil component in industrial gear oils, compressor oils, and hydraulic fluids, TOPM's wide operating temperature range (pour point −27°C to flash point 270°C), VI 98, and oxidative stability extend drain intervals vs mineral oil.
4. High-Temperature PVC, Metal Processing Fluids, Coatings & Adhesives
High-temperature resistant PVC - cables & sealing materials: In heat-resistant PVC insulation for automotive wiring (>105°C service), industrial high-temperature cables, and sealing materials for elevated-temperature service, TOPM's high boiling point and low volatility prevent plasticiser loss during service, extending cable and seal service life versus lower-MW plasticisers that volatilise progressively at elevated temperatures. TOPM's compatibility with automotive cable PVC compound recipes is established across major automotive harness manufacturers.
Metal processing fluids: TOPM's low vapour pressure and thermal stability prevent decomposition and fume generation under the heat of cutting, grinding, and stamping operations. Its ester polar groups form a tenacious boundary lubricant film on tool-workpiece interfaces, improving workpiece surface finish and extending tool life. Low ambient volatility simplifies workplace vapour management in metal processing environments.
Coatings, adhesives & inks: High-boiling permanent plasticiser and flexibiliser in heat-resistant coatings, structural adhesives, and specialty printing inks exposed to elevated service temperatures. TOPM's thermal stability, compatibility with aromatic resin systems, and non-CMR profile contribute heat resistance, low migration, and flexibility in formulations for demanding industrial service environments.
TOPM vs TOTM vs DEHP vs PAO - Synthetic Ester Selection Guide
| Property | DEHP / DOP CAS 117-81-7 |
TOTM CAS 3319-31-1 |
PAO 10 (Group IV) | TOPM CAS 3126-80-5 |
|---|---|---|---|---|
| Ester Type | Di-ester phthalate | Tri-ester trimellitate | Polyalphaolefin (0 ester) | Tetra-ester pyromellitate ↑ |
| Mol. Weight (g/mol) | ~391 | ~547 | ~450–600 | 703 ↑ highest monomeric |
| Flash Point (°C) | ~185 | ~245 | ~246 (PAO 10) | ≥265 ↑ |
| Evap. Loss (250°C, 1h) | ~3–5% ⚠ | ~1.5–2% | ~2–4% (lower MW) | 1.0% ↓ lowest |
| Viscosity Index | ~90 | ~90 | ~138 ✓ | 98 |
| Polar Solvency | Moderate | Good | Very low ⚠ | Excellent ↑ (4 ester dipoles) |
| EU CLP Repr. 1B | Repr. 1B ⚠ | Not classified ✓ | N/A ✓ | Not classified ✓ |
| REACH Annex XIV | Listed ⚠ | Not listed ✓ | Not listed ✓ | Not listed ✓ |
| Medical PVC Use | Restricted / phasing out ⚠ | Permitted (lower tier) | N/A | Preferred ultra-low-tox ✓ |
| High-Temp Chain Oil | Insufficient stability ⚠ | Good | Good | Best in class ✓ |
TOPM Regulatory Status - Clean Profile Enabling Medical & Industrial Applications
Storage, Handling & Safety - Simplest Profile in the Portfolio
Storage
Store at 5–30°C in sealed steel drums or HDPE containers. TOPM remains liquid and pumpable at all storage temperatures above 0°C (pour point −27°C). Standard combustible liquid storage area - no explosion-proof electrical equipment required (flash point ≥265°C, Class III-B).
Keep containers sealed: TOPM absorbs moisture slowly from air, increasing acid value through slow ester hydrolysis over time. Segregate from strong oxidisers and strong bases (accelerate ester hydrolysis at elevated temperatures). Compatible with common metals (steel, aluminium, stainless steel) and polymers (HDPE, PTFE).
Shelf life: 12 months in original sealed packaging at 5–30°C. Retest acid value if stored more than 9 months before use in acid-sensitive applications (medical PVC, lubricant formulations). Maximum 3-layer drum stacking.
PPE & Handling
GHS hazards: Mild skin irritant (Category 3) at most. No flammability hazard at ambient. No CMR. No reproductive hazard. No vapour inhalation risk at ambient temperature.
Gloves: Nitrile (≥0.1 mm) for routine handling - primary hazard is mild skin irritation. Safety goggles for transfer operations. General ventilation adequate at ambient temperature (negligible vapour pressure below 100°C).
Heated processes above 150°C: Local exhaust ventilation recommended to capture any thermal decomposition products (ester pyrolysis products at high temperature).
Spill: TOPM is viscous and slow-spreading at ambient. Absorb with vermiculite or dry sand; dispose as non-hazardous industrial ester waste. Full occupational safety data: GESTIS CAS 3126-80-5 ↗
Frequently Asked Questions about TOPM / TEHPM
Q: What is the difference between TOPM and TOTM - and when should I choose TOPM?
TOPM (pyromellitate) has four ester groups at all four positions of the benzene ring; TOTM (trimellitate) has three ester groups at the 1,2,4-positions. This one additional ester group produces: higher MW (703 vs 547 g/mol), lower evaporation loss (1.0% vs ~1.5–2.0% at 250°C/1h), less carbon deposition in 260°C/3h chain oil tests, further reduced migration from PVC matrices, and higher polar solvency for additive packages. Choose TOPM when: (1) continuous operation above 220°C and carbon deposit minimisation is critical; (2) medical-grade PVC compliance requires minimum extractable plasticiser content; (3) Group III/IV lubricant formulation requires maximum additive solubility. Choose TOTM when lower cost is the priority and the highest-temperature performance is not required.
Q: How is TOPM used as a lubricant additive versus a primary base oil?
As a functional additive at 5–20% in PAO or Group III formulations, TOPM's polar ester groups solubilise the additive package (ZDDP, amine antioxidants, friction modifiers) that has poor solubility in non-polar highly refined base oils - preventing additive dropout, phase separation on storage, and loss of anti-wear and anti-oxidant performance in all-PAO formulations. TOPM also provides elastomer seal compatibility management (1–5% addition). As a primary synthetic base oil at 40–100% in high-temperature chain oil formulations, TOPM provides the bulk thermal-oxidative stability, low evaporation loss, and low carbon deposit performance - typically combined with aminic antioxidant (0.5–2%), EP anti-wear agent (0.5–2%), and anti-foam (0.1%) to create a complete high-temperature chain oil meeting DIN 51825 or customer specification.
Q: Is TOPM suitable for medical-grade PVC - what extraction and toxicity data is available?
TOPM is the industry-recognised ultra-low-toxicity plasticiser for medical PVC, qualified across a broad range of cleared medical devices. Key supporting data: high MW (703 g/mol) reduces diffusion rate through the PVC matrix; compatibility with PVC produces a thermodynamically stable plasticised system with very low migration driving force; extraction testing in simulated body fluids (saline, lipid emulsion, citrate buffer) shows TOPM migration well below biological effect thresholds; ISO 10993-5 cytotoxicity and ISO 10993-4 haemocompatibility testing on TOPM-plasticised PVC have confirmed acceptable biocompatibility in preclinical evaluations. Sinolook provides medical-grade TOPM with enhanced COA, batch-specific extraction data, and an ISO 10993 biocompatibility pre-screening summary for medical device technical file preparation.
Q: Why does TOPM have such a high viscosity index (VI 98) - and what does this mean in practice?
Viscosity index measures how much a lubricant's viscosity changes with temperature - higher VI means more stable lubrication film thickness across the operating temperature range. TOPM's VI of 98 (actual test value) compares favourably with Group II mineral oil (VI ~95–100) and approaches the 100–120 range of PAO base oils. In practical terms, for a high-temperature chain oil spanning ambient (25°C) to oven operating temperature (250°C+), TOPM maintains the minimum required film thickness at the upper temperature extreme while providing adequate viscosity for cold-start and ambient protection. This wide-range viscosity stability - combined with TOPM's flash point ≥265°C and pour point −27°C - gives high-temperature chain oil formulators a full-spectrum lubricant base that does not require viscosity modifying polymers for wide-temperature-range performance.
Authoritative Technical & Regulatory References
ECHA substance page for tetraoctyl pyromellitate: confirming no CMR classification, REACH registration, absence of SVHC listing, and no Annex XIV or Annex XVII restrictions.
NCBI PubChem compound record: IUPAC name, molecular formula C₄₂H₇₀O₈, molecular weight 703.01 g/mol (correct value), GHS classification, and physicochemical data for TOPM / TEHPM.
EPA CompTox Dashboard for CAS 3126-80-5: TSCA inventory listing, non-HAP confirmation under Section 112(b) of the Clean Air Act, and physicochemical property data.
ECHA substance page for DEHP - showing Repr. 1B (H360FD) classification and REACH Annex XIV listing that TOPM avoids, directly illustrating TOPM's regulatory advantage as the medical-grade DEHP replacement.
ECHA substance page for TOTM - the three-ester trimellitate reference compound for performance and regulatory comparison with TOPM's four-ester pyromellitate architecture.
IFA GESTIS substance database for CAS 3126-80-5: occupational safety classification, physicochemical data, and health hazard summary confirming TOPM's low-hazard profile under normal industrial handling.
Buy TOPM / TEHPM from China · Medical-Grade & Industrial Grade · No CMR · Best-in-Class Chain Oil Performance
Request TOPM Price, Qualification Sample & Regulatory Documentation
Sinolook supplies Tetraoctyl Pyromellitate (TOPM / TEHPM, CAS 3126-80-5) in industrial grade (VI ≥95, pour point ≤−18°C, evaporation loss ≤1.5% @ 250°C/1h, flash point ≥265°C) and medical grade (Pt-Co ≤50, heavy metals, ISO 10993 pre-screening data, extraction test data). Qualification samples 0.5–5 kg at nominal charge. Volume from 200 kg drums to ISO tanks. Lead time 10–15 business days. Response within 24 hours.
Related products: TOTM (Tris(2-ethylhexyl) Trimellitate) - three-ester trimellitate comparator · Maleic Anhydride (MAH) · NMP (N-Methyl-2-pyrrolidinone) · PGMP (Propylene Glycol Monomethyl Ether Propionate) · Propionic Anhydride
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